1. Field of the Invention
The present invention relates to a tape reel around which magnetic tape for recording information is wound and to an information recording medium equipped with such tape reel.
2. Description of the Related Art
As one example of an information recording medium that can record a large amount of data, in Japanese Laid-Open Patent Publication No. 2002-100148, the present applicant has disclosed a single-reel-type tape cartridge according to LTO (Linear Tape Open) standard. This tape cartridge is constructed of a main case including an upper case and a lower case that can engage one another, a single tape reel that is rotatably enclosed inside the main case and around which a magnetic tape (tape) is wound, and the like. In this case, the tape reel is constructed of an upper flange and a hub in the shape of a bottomed cylinder at whose lower end a lower flange is integrally formed.
By investigating the above technology, the present inventors discovered the following problem to be solved. That is, the tape reel in the tape cartridge is manufactured by injection molding resin. Here, to prevent damage to or stretching of the magnetic tape during winding, it is preferable for an outer circumferential surface of the hub to be formed smooth. Accordingly, to prevent the production of convexes and concaves in the outer circumferential surface of the hub due to “sinking” during injection molding, the hub of the tape reel is formed comparatively thinly. On the other hand, when the magnetic tape is wound around the tape reel, a constant tension is applied to the magnetic tape to prevent the production of wrinkles due to the tape becoming slack. This means that in a state where the magnetic tape has been wound out, a large force is applied to the hub due to the magnetic tape being tightened. As a result, as shown in FIG. 20, a hub 332 that is formed thinly is caused to deform slightly due to such force, and as the hub 332 deforms, there is the risk of the front end of an upper flange 331 becoming inclined downward and the front end of a lower flange 333 becoming inclined upward. Accordingly, to prevent the upper flange 331 and the lower flange 333 from contacting the ends of the magnetic tape T, sufficient clearance should preferably be provided between the upper flange 331 and the lower flange 333.